Authorities announced on Sunday that Sullivan was arrested in Georgia after staff at a hospital where she was seeking treatment became aware that she was a fugitive from Utah.

The Cherokee County Sheriff's Office in Georgia confirmed she was arrested without incident. Police say Kitzmiller was arrested Friday.

While investigators don't believe Sullivan was directly responsible for any of the abuse the boy is believed to have suffered, she faces the same count of first-degree murder as Kitzmiller.

"Both of them were charged because the girlfriend indicated that there was a level of abuse that was going on, she was aware of this abuse, and she took no steps to stop this or to take the child to safety," the district attorney told reporters.

Prosecutors allege Kitzmiller was both using heroin and abusing the boy regularly before his death Sept. 17.

On that night, Sullivan told cops she was on the phone telling a friend she wanted to get away from Kitzmiller when she found the baby behaving strangely.

Sullivan said Kitzmiller had been watching the boy at the time. Sullivan said she picked up the baby and he seemed calmer, so she put him to bed.

However, when she later checked on the boy, Sullivan told investigators he made "grunting" and "gasping" noises before he became unresponsive.

When emergency responders arrived, he could not be revived.

Authorities say there was "bruising around the infant's eyes" when he was found. According to the criminal complaint, an autopsy showed the infant had gone from 5 pounds at birth to 4 pounds at the time of his death.